Astigmatism Research Today is a free monthly online journal that collates and summarizes the latest research about Astigmatism, including details on cornea, retina, treatment, types, signs, tests.

Refractive, biometric and topographic changes among Portuguese university science students: a 3-year longitudinal study.

Jorge J, Almeida JB, Parafita MA

Department of Physics (Optometry), School of Sciences, University of Minho, Campus de Gualtar, Braga, Portugal. jorge@fisica.uminho.pt

PURPOSE: The aim of this study was to investigate the changes in refractive, biometric and topographic ocular parameters among university students in Portugal during a 3-year period. METHODS: A 3-year longitudinal study comprised 118 Portuguese university students from the School of Science (34 males and 84 females; mean age 20.6 +/- 2.3 years). Ocular refraction, corneal curvature (CR) and eccentricity, and A-scan biometry were conducted under cycloplegia. The sphero-cylindrical refractive results were converted into vector representations (M, J(0) and J(45)) for statistical analysis. Myopia was defined as M < or = -0.50 D, emmetropia as M > -0.50 D and < +0.50 D and hyperopia as M > or = +0.50 D. RESULTS: At the beginning of the study sphero-cylindrical refraction (M) ranged from -6.75 to +3.00 D, with a mean value of 0.23 +/- 1.46 D [mean +/- standard deviation (S.D.)]. Eighty-three students presented astigmatism with a mean value (+/-S.D.) of -0.52 +/- 0.41 D, and a maximum of -2.25 D. After 3 years the mean refractive change for the M component was -0.29 +/- 0.38 D (p < 0.001) and non-significant changes of 0.02 +/- 0.16 D (p = 0.281) for the J(0) component and 0.01 +/- 0.09 D (p = 0.784) for the J(45) component. Prevalence of myopia increased by 5.1%, while the prevalence of hyperopia decreased by 9.4%. Myopia progression > or =0.5 D was observed in 22% of the population. Axial length, vitreous chamber depth and lens thickness increased significantly while anterior chamber depth and central CR did not change significantly. CONCLUSIONS: This study shows a change in refraction towards myopia accompanied by a vitreous chamber elongation in a Portuguese population comprising science students during the first three years of their university course. Younger students were more likely to show clinically significant myopia progression.

Published 1 May 2007 in Ophthalmic Physiol Opt, 27(3): 287-94.
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